The influence of environment on the morphology of Macrobrachium australiense (Decapoda : Palaemonidae)

The common endemic Australian freshwater prawn, Macrobrachium australiense is recognised as having potential as a culture species. Across the species' natural range high variation exists for external morphological traits of relevance to culture. Previous studies have demonstrated that morphological variation can often be correlated with environmental factors. The current study demonstrated that when exposed to a controlled environment, offspring of two morphologically divergent wild stocks retain little of their parental morphological characteristics. When crossed and grown under identical conditions, 'hybrids' and pure offspring were morphologically uniform. A breeding and growth trial of offspring within a single stock were exposed to a variety of environmental temperatures that resulted in high variability of morphological traits in the offspring. These results suggest that environmental parameters rather than genotype may strongly influence the phenotypic expression of the morphological traits investigated. Morphological traits of interest to culture, such as abdomen length and width show low additive genetic variance and hence may not respond well to traditional selective breeding approaches designed to improve their attributes.